1. Field of the Invention
This invention relates to a process for the propylation of toluene under controlled temperature conditions in the presence of a specified crystalline aluminosilicate zeolite catalyst.
2. Description of the Prior Art
Alkylation of aromatic hydrocarbons utilizing crystalline aluminosilicate catalysts has heretofore been described. U.S. Pat. No. 2,904,607 to Mattox refers to alkylaion of aromatic hydrocarbons with an oelfin, e.g., toluene with propylene at a temperature of 850.degree. F. in the presence of a crystalline metallic aluminosilicate having uniform pore openings of about 6 to about 15 Angstrom units. U.S. Pat. No. 3,751,504 to Keown et al. and U.S. Pat. No. 3,751,506 to Burress describe vapor phase alkylation of aromatic hydrocarbons with olefins at a temperature between about 650.degree. F. and about 900.degree. F. in the presence of a ZSM-5 type zeolite catalyst.
While the above-noted prior art is considered of interest in connection with the subject matter of the present invention, the propylation reaction described herein carried out at a temperature between about 400.degree. F. and about 600.degree. F. in the presence of a catalyst of a crystalline aluminosilicate zeolite having a silica to alumina ratio of at least about 12 and a constraint index within the approximate range of 1 to 12 to selectively yield cymene in preference to normal propyl toluene has not, insofar as is known, been heretofore described.